Application of a Single-Antenna GPS–Based Attitude Estimation on the Stability Control of a Small Unmanned Aerial Vehicle

Abstract

Attitude estimation is an important issue in the autonomous flight of an unmanned aerial vehicle (UAV) system. However, for a micro-sized UAV with a wingspan of less than 2 m, a high performance Attitude and Heading Reference System (AHRS) is usually too heavy and large, whereas a low-cost AHRS of suitable size and weight may easily give erroneous attitude data. In this study, a single-antenna global positioning system (GPS)–based attitude estimation method, called pseudoattitude, in combination with the angular rate data given by the onboard gyroscopes, is applied to solve the problem. That is, the pseudoattitude estimated by the GPS velocity data provides a reference attitude with some time lag, whereas the gyroscope’s angular rate is integrated with the aid of a proposed complementary filter to eliminate the time lag problem. An experimental method is then developed to determine the filter parameters by a static ground test of the GPS and flight test data with postprocessing and analysis. A fuzzy logic attitude controller is designed for the experimental verification of the attitude estimation. Results indicate that the attitude estimation is successfully obtained and used as the primary attitude source to stably control the UAV in this study. During the flight tests, two sets of desired attitude conditions (desired roll: 0°, desired pitch: 0° and desired roll: